TRENTON A Senate panel on Monday advanced a proposal to restore funding to New Jersey's depleted open-space program by amending the state's constitution to dedicate a portion of revenue from the corporate business tax to preserving land.

The plan drew cautious optimism from environmental groups, which agree in principle on the need to fund open-space preservation but are wary of diverting money from other eco-friendly causes.

Specifically, the amendment would dedicate 6 percent of corporate business tax revenue - about $150 million annually - to the preservation of open space, farmland, and historic sites for 30 years. It would take effect in fiscal year 2016.

It also would end the diversion of 4 percent of the same tax toward water quality programs, hazardous site cleanups, air pollution, and other environmental programs.

Some of that lost funding would be replaced by tapping into natural resource damages and fines of polluters.

The state has not dedicated stable funding to open space since voters approved $400 million in land-preservation bonds in 2009. That money has since been spent.

"We're in a crisis on open space," said Bob Smith (D., Middlesex), chairman of the Environment and Energy Committee. "The tank is empty."

Smith's committee tried to put the issue to voters last year as well, with a proposal to siphon off $200 million a year from the state's sales tax for land preservation. The Senate approved the measure, but the Assembly disagreed with using sales tax revenues to fund the bill.

The committee advanced the latest idea by a 4-1 vote, with Samuel Thompson (R., Middlesex) against it.

"It doesn't create any new revenue," Thompson said, likening the proposal to "robbing Peter to pay Paul."

The proposal is not a perfect solution, said Sen. Christopher "Kip" Bateman (R., Somerset), a cosponsor, "but it's important to the future of our state to have permanent funding."

Environmentalists acknowledged the urgency of the matter at Thursday's hearing and supported the plan with the understanding that it might require changes.

"We're in a race to the death if we don't get this done," said Eileen Swan, policy manager for the New Jersey Conservation Foundation.

Supporters still voiced concerns. Ed Potosnak, executive director of the New Jersey League of Conservation Voters, objected to using natural resource damages and fines collected from violations of environmental law to fund open-space preservation.

"These funds are unpredictable and should be used for environmental restoration projects," he said. "New Jersey has a toxic legacy. We want to make sure those funds are there to clean up those properties."

Smith acknowledged another problem: some of the $100 million already diverted from the corporate business tax has not gone toward the environmental programs for which the money was intended.

He and others said the Christie administration had spent some of the money on Department of Environmental Protection staff salaries.

"If that money is not currently being used for the cleanup of contaminated sites . . . then we believe the funding should be returned back to folks who paid that tax," said Ed Waters, director of government affairs for the Chemistry Council of New Jersey.

In an e-mail, a spokesman for Gov. Christie said the law allows for corporate business tax revenue to go toward administration of the environmental programs.

"How could you allocate money for such programs but not include funds for those who actually administer and oversee the programs? That just doesn't make any sense," spokesman Kevin Roberts said.

The bill was referred to the Budget and Appropriations Committee. The Assembly passed a different version of the bill last session, which calls for a $200 million bond referendum. A Democratc aide said the Asembly leadership would review the bill but, "At this moment, no action is planned."